Search results for "Poles"
showing 10 items of 64 documents
Plantar Pressure Differences Between Nordic Walking Techniques
2017
Abstract High plantar pressure has been associated with increased risk of injury. The characteristics of each physical activity determine the load on the lower limbs. The influence of Nordic Walking (NW) technique on plantar pressure is still unknown. The aim of this study was to analyze the differences between plantar pressure during NW with the Diagonal technique (DT) versus Alpha technique (AT) and compare them with the pressure obtained during normal walking (W). The normality and sphericity of the plantar pressure data were checked before performing a two-way repeated measures ANOVA in order to find differences between speeds (preferred, fast) and the gait (NW, W) as within-subject fac…
Pool choice in a vertical landscape: Tadpole‐rearing site flexibility in phytotelm‐breeding frogs
2021
Abstract Many species of Neotropical frogs have evolved to deposit their tadpoles in small water bodies inside plant structures called phytotelmata. These pools are small enough to exclude large predators but have limited nutrients and high desiccation risk. Here, we explore phytotelm use by three common Neotropical species: Osteocephalus oophagus, an arboreal frog that periodically feeds eggs to its tadpoles; Dendrobates tinctorius, a tadpole‐transporting poison frog with cannibalistic tadpoles; and Allobates femoralis, a terrestrial tadpole‐transporting poison frog with omnivorous tadpoles. We found that D. tinctorius occupies pools across the chemical and vertical gradient, whereas A. fe…
Finite-energy sum rules in eta photoproduction off a nucleon
2016
The reaction ${\gamma}N \to {\eta}N$ is studied in the high-energy regime (with photon lab energies $E_{\gamma}^{\textrm{lab}} > 4$ GeV) using information from the resonance region through the use of finite-energy sum rules (FESR). We illustrate how analyticity allows one to map the t-dependence of the unknown Regge residue functions. We provide predictions for the energy dependence of the beam asymmetry at high energies.
Structure of pion photoproduction amplitudes
2018
We derive and apply the finite energy sum rules to pion photoproduction. We evaluate the low energy part of the sum rules using several state-of-the-art models. We show how the differences in the low energy side of the sum rules might originate from different quantum number assignments of baryon resonances. We interpret the observed features in the low energy side of the sum rules with the expectation from Regge theory. Finally, we present a model, in terms of a Regge-pole expansion, that matches the sum rules and the high-energy observables.
Brief an Johann G. Herder.
1799
Ms. 930a, Nr. 17, Bl. 43r-44v Garlieb H. Merkel. Brief an Johann G. Herder. Berlin, d[en] 9ten März 1799 Autora rokraksts / Autograph, vācuval. / Deutsch [4] lpp. / S. Attēlu numuri / Bildnummern: 930a-017-1, 930a-017-2-3, 930a-017-4 Wahrscheinlich handelt es sich bei diesem Dokument um ein Konzeptdes Briefes von Merkel an Herder; es ist also nicht gesichert, ob dieser in Reinschrift verfasst undan den Adressaten abgeschickt wurde. Merkel schreibt sehr persönlich über sich selbst und versucht das Bild eines draufgängerischen Lebemannes zu geben, der seinen Horizont, wenn möglich, lieber durch eigene Erfahrungen als durch Buchlektüre erweitern will. Merkel weiß, dass er diese Sichtweise mit …
Design of a Compact Dual Circular-Polarized Antenna for L-Band Satellite Applications
2020
In this paper, we propose the design of a dual circular-polarized antenna for L-band applications (1.1-1.6 GHz). The designed antenna has been developed by considering crossed-dipoles on top of which a circular patch has been placed to properly act on the mutual coupling between the dipoles. The dual circular polarization is achieved by feeding dipoles in quadrature. Moreover, to increase the antenna gain and polarization purity at high elevation angles, a fence of passive monopoles has been added. The proposed antenna can profitably used as primary feed of a low-frequency parabolic reflector.
Hidden Dirac Monopoles
2008
Dirac showed that the existence of one magnetic pole in the universe could offer an explanation of the discrete nature of the electric charge. Magnetic poles appear naturally in most grand unified theories. Their discovery would be of greatest importance for particle physics and cosmology. The intense experimental search carried thus far has not met with success. I proposed a universe with magnetic poles which are not observed free because they hide in deeply bound monopole--anti-monopole states named monopolium. I discuss the realization of this proposal and its consistency with known cosmological features. I furthermore analyze its implications and the experimental signatures that confirm…
Pole positions and residues from pion photoproduction using the Laurent-Pietarinen expansion method
2014
We have applied a new approach to determine the pole positions and residues from pion photoproduction multipoles. The method is based on a Laurent expansion of the partial wave T-matrices, with a Pietarinen series representing the regular part of energy-dependent and single-energy photoproduction solutions. The method has been applied to multipole fits generated by the MAID and GWU/SAID groups. We show that the number and properties of poles extracted from photoproduction data correspond very well to results from $\pi$N elastic data and values cited by Particle Data Group (PDG). The photoproduction residues provide new information for the electromagnetic current at the pole position, which …
Introducing the Pietarinen expansion method into the single-channel pole extraction problem
2013
We present a new approach to quantifying pole parameters of single-channel processes based on a Laurent expansion of partial-wave T matrices in the vicinity of the real axis. Instead of using the conventional power-series description of the nonsingular part of the Laurent expansion, we represent this part by a convergent series of Pietarinen functions. As the analytic structure of the nonsingular part is usually very well known (physical cuts with branch points at inelastic thresholds, and unphysical cuts in the negative energy plane), we find that one Pietarinen series per cut represents the analytic structure fairly reliably. The number of terms in each Pietarinen series is determined by …
Monopolium: the key to monopoles
2007
Dirac showed that the existence of one magnetic pole in the universe could offer an explanation for the discrete nature of the electric charge. Magnetic poles appear naturally in most Grand Unified Theories. Their discovery would be of greatest importance for particle physics and cosmology. The intense experimental search carried thus far has not met with success. Moreover, if the monopoles are very massive their production is outside the range of present day facilities. A way out of this impasse would be if the monopoles bind to form monopolium, a monopole- antimonopole bound state, which is so strongly bound, that it has a relatively small mass. Under these circumstances it could be produ…